I would recommend 'When Lily Chooses Snape'. This fanfiction is quite well - written, with a great balance of dialogue and description. It makes you really believe in the possibility of Lily choosing Snape. Another one is 'Lily's Decision for Snape' which goes into the backstories of both characters and how that influences Lily's choice. Also, 'Snape and Lily: The Chosen Path' is a great piece that not only focuses on their relationship but also on how it affects the fates of other characters in the Harry Potter universe.
You can try Archive of Our Own (AO3). It has a vast collection of fanfictions, and there are likely many stories about Lily choosing Snape there. Fanfiction.net is also a good place to look. It has been around for a long time and has a large number of Harry Potter - related fanfictions.
One popular Snape and Lily fanfiction is 'The Lily and the Prince'. It delves deep into their relationship, exploring their early years at Hogwarts. The story beautifully portrays Snape's complex feelings for Lily.
There's also 'The Confrontation' in which the story might build up tension between Lily and Snape over time. Maybe Snape says something really offensive, and Lily, being the strong - willed character she is, punches him as a form of standing up for herself and her values.
One great Lily Evans and Severus Snape fanfiction is 'The Prince's Tale Reimagined'. It delves deeper into their relationship, exploring the moments that led to their friendship's fracture. Another one is 'Lily's Perspective'. This fanfic gives readers a chance to see the events from Lily's point of view, which is really interesting as it shows how she might have felt about Severus at different stages of their lives. There's also 'Severus and Lily: Lost Moments' which focuses on the forgotten or overlooked interactions between them.
A great fanfiction in this regard is 'Snape and Lily: Against the Marauders'. It really delves into the reasons why Lily and Snape might despise the Marauders. It could be due to their pranks that often cross the line or their sometimes arrogant attitudes. The story also shows how this shared feeling affects their own friendship and how they interact with others in Hogwarts.
One possible theme is loyalty. Snape's loyalty to Lily was unwavering, and fanfictions can explore how that loyalty manifested in different situations, like when he had to choose between the Death Eaters and protecting Lily. Another theme could be regret, as Snape may have regretted some of his actions that affected his relationship with Lily.
Well, a lot of fanfictions depict Snape's love for Lily as a silent, internal struggle. He doesn't always show it outwardly, but it's always there, burning inside him. Some stories show how his love for her makes him protect Harry, not because he likes Harry, but because Harry is a part of Lily. This love is also sometimes shown as a complex emotion that is intertwined with his sense of self - worth. He feels unworthy of her love, but still can't let go of his feelings, and this internal conflict is explored in great detail in many fanfictions.
Fanfictions often show Snape's unrequited love through his inner thoughts. He might be constantly thinking about Lily while she's with James. For example, he'll watch her from afar and have these deep, melancholic musings about what could have been.
The Snape hurts Lily fanfictions can be quite a departure from the traditional view of their relationship. It could be that the writer wants to explore the what - ifs. What if Snape's dark side overcame his love for Lily? His hurtful actions towards her could then be used as a device to show the growth or downfall of his character. For example, it might lead to his ultimate redemption or his complete fall into darkness, all while Lily is at the center of this complex dynamic.
One interesting 'Harry Potter Snape Lily' fanfiction is 'The Lily and the Prince'. It delves deep into Snape's unrequited love for Lily. Another one could be 'Lily's Influence on Snape', which shows how Lily's presence shaped Snape's character throughout his life. There's also 'Snape's Memories of Lily', which focuses on Snape's most precious memories of her.